Quantifying the local tissue volume and composition in individual brains with magnetic resonance imaging

Abstract

We describe a quantitative neuroimaging method to estimate the macromolecular tissue volume (MTV), a fundamental measure of brain anatomy. By making measurements over a range of field strengths and scan parameters, we tested the key assumptions and the robustness of the method. The measurements confirm that a consistent, quantitative estimate of macromolecular volume can be obtained across a range of scanners. MTV estimates are sufficiently precise to enable a comparison between data obtained from an individual subject with control population data. We describe two applications. First, we show that MTV estimates can be combined with T1 and diffusion measurements to augment our understanding of the tissue properties. Second we show that MTV provides a sensitive measure of disease status in individual patients with multiple sclerosis. The MTV maps are obtained using short clinically appropriate scans that can reveal how tissue changes influence behavior and cognition.

Computationale Neuroanatomie und Mikrostrukturbildgebung mit der Magnetresonanztomographie

“…T1, T2, T2*, PD und MT hängen unter anderem vom makromolekularen Gehalt ab und werden daher als Biomarker für Myelinisierung verwendet [12][13][14][15]. Die Diffusionsbildgebung [16,17] Abb.…”

“…1c). Geometrische Informationen, die durch Faserverbindungen charakterisiert werden, können die Spezifizität solcher Modelle weiter verbessern [15,54].…”

Synthetic quantitative MRI through relaxometry modelling

“…Going beyond physical models that describe the MRI signal as a function of scanner parameters, such as flip angle, repetition and echo times, biophysical models that describe the interdependence of MRI parameters, such as R 1 , proton density (PD) and macromolecular tissue volume fraction, have more recently been proposed 9, 10, 11. Combining such models with the concept of synthesizing images points towards an alternative approach: synthetic qMRI.…”

Abnormal White Matter Properties in Adolescent Girls With Anorexia Nervosa

“…We address this issue in the present study by exploring whether white matter tissue properties differ in a sample of adolescent girls with AN as compared to an agematched sample of girls of normal weight and eating behaviors. To achieve this overall aim, we used two advanced structural neuroimaging techniques for assessing white matter microstructure: diffusion MRI (dMRI) analyzed with tractography and a novel quantitative magnetic resonance imaging (qMRI) method for measuring T1 relaxometry, R1 (1/T1), reflecting myelin content (Mezer et al, 2013).…”

“…Advances in qMRI methods now allow for the measurement of R1 with clinically-feasible scan times (Lutti et al, 2010;Mezer et al, 2013;Yarnykh, 2010). Techniques for mapping R1 have been combined with dMRI to assess changes in white matter tissue composition in relation neurological disorders known to affect myelin, such as multiple sclerosis (Mezer et al, 2013), and to dissociate among biological processes contributing to white matter changes observed during development and aging (Yeatman et al, 2014). To our knowledge, the present study is the first to employ both dMRI and R1 mapping techniques to evaluate white matter tissue properties in AN during adolescence.…”